Copying pad and method of preparing same



Patented Nov. 9, 1937 PATENT OFFICE COPYING PAD AND METHOD OF PREPAR-ING SAME William Hoskins, In, La Grange, Ill., asslgnor to Ditto,Incorporated, Chicago, Ill., a corporation of West Virg nia No Drawing.Application May 23, 1936, Serial No. 81,513

Claims. (01. 41-315) The present invention relates to improvedhectograph copying pads or similar gelatinous copying pads and tomethods of preparing the same.

' Copy pads and bands of the hectograph type 5 usually comprise abacking of paper, cloth or other suitable fabric and a'ccating or layerof some suitable gelatinous copying mass, which are bonded together byan intermediate layer or iilm formed from a drying oil such as linseedoil or o the like. In the preparation of copying pads as hithertocarried out, the paper or fabric backing is first coated with asiccative oil such as linseed oil, tung oil, Perilla oil or the like,and u the coating is then permitted to dry under normal atmosphericconditions until the coating hardens, forming a film or layer. Thisdrying step usually takes from two to eight days. The prepared backingis then coated with a layer of some suitable gelatinous copying mass andthe finished pad then shipped orstored for use. This method isobjectionable from the standpoint of the prolonged waiting timenecessary to permit the intermediate siccative oil bonding layer to drywhich necessitates the provision of large drying space and storagecapacity; and because the bonding layer may in some cases harden undulyor fail to produce a bond of the required permanence.

In accordance with the present invention, I have found that the inherentdisadvantages of the prior method of forming copying pads are overcomeif a sulphonated oil product derived from a" drying, semi-drying ornon-drying oil is utilized as, or as a constituent of, the intermedi- 3ate bonding layer between the backing-and the copy mass. Not only doesthe sulphonated oil lend itself readily to quick drying by natural orartificial means, but the film formed is flexible and provides apermanent and effective bond between the backing and the gelatinous copymass.

The copy mass embodied in the present invention may be suitably agelatinous copying mass of the type frequently referred to as ahectographic copy massj for example I may employ tanned gelatinouscopying masses having suitable proportions of tanning agents, such asformaldehyde, alum or the like, or of light sensitive tanning agentssuch as the chromates or dichromates;' or I may use hardened gelatinouscopymeans, containing a glyceride of starch, as described and claimed inmy prior co-pending application, Serial No. 48,495, filed November 6,1935. u In carrying out: the Present invention, I may employ as theintermediate bonding layer a water-soluble sulphonated oil, as forexample sulphonated castor oil, sulphonated ricinoleic acid, Turkey redoil or the like. The sulphonated emulsiflable oil product may be applieddirectly or in solution to a sized cloth or paper or other suitablebacking or I may incorporate the oil into a conventional sizingcomposition and apply it as such to the fabric backing to impregnate andcoat the same. 10

Thus, I may employ for treating the fabric backing, an aqueous solutionof a sizing composition containing suitably from about 3% upwardly ofthe sulphonated oil such as Turkey red oil or sulphonated castor oil.The proportion of sulphonated oil employed may be varied widely and mayconstitute as much as 25% to 50% of the size solution or even higher. Asan example of a suitable size containing the sulphonated oil, thefollowing, containing approximately 5% of sulphonated oil, has beenfound satisfactory:

The sizing composition containing the sulphonated oil is applied in anydesirable manner to the paper, cloth or other suitable fabric backm ingand treated with a tanning agent to insolubilize the coating. Ifdesired, suitable quantities of tanning agents, such as formaldehyde,aluminum alums'or chrome alums may be employed in the mixture inproportions to secure some tanning action in the size.

The sized fabric backing containing the sulphonated oil is now quicklydried in any desirable manner, as for example by dry preheated air orgas, and is then coated with a layer of a gela- 40 tinous copying mass,suitably of the character above referred to. The drying may be rapidlyeffected-as it is dependent upon various factors such as thickness ofthe sulphonated oil film, humidity, temperature of the heated air orother suitable heating means, etc. and not upon chemical, oxidizing orpolymerizationreactions as in the case of the bonding agents hithertoused. I have found that a backing treated in accordance with myinvention may be suitably dried by heated air in about one-half hour.0bviously however, my invention is not dependent upon the exactitude ofthe time interval necessary to dry the sulphonated oil layer or film.

As set forth above, the sulphonated oil such as Turkey redoil,sulphonated castor oil or like I the oil may be eflectively used as theintermediate bonding layer. A 25% solution has been successfullyused,'and it is possible to utilize 50% solutions or even thesulphonated oil per se; however, these higher concentrations of thesulphonated oil are not necessary for the desired unlformly thin coatingis more readily obtained at the lower concentrations.

The sulphonated oil product thus applied to and forming a surfacecoating on the backing serves to eflectively and permanently bond thesurface copy mass layer to the backing.

I1 desired, the copy mass may be applied to the sized or coated backingwhile the latter is still wet and the composite copy pad may then be setby cooling or in any desirable manner.

While I have described a preferred sizing composition containing thesulphonated oil, it is obvious that my invention is not to be construedas limited thereto, for the sulphonated oil may be used in conjunctionwith any conventional siu either in admixture therewith or applied to abacking treated therewith.

In the specification, the expression copying pads is used to includepads in the form of long bands as used in rolls on copying machines aswell as shorter pads and other forms of copying pads.

Although the present invention has been described in connection with thedetails of specific examples thereof, it is to be understood that it isnot limited thereby except insofar as included in the accompanyingclaims.

I claim:

1. A; copy pad comprising a backing, a copy mass and an intermediatebonding layer of a sulphonated oil.

2. A copy pad having a backing, a flexible bonding coating comprising asulphonated oil on said backing and a layer or a copy mass on saidcoating.

3. A copy pad having a backing, a flexible bonding coating of asulphonated oil on said backing and a layer of a gelatinous copy mass onsaid coating.

4. A copy pad having a backing and a gelatinous copy mass, the copy massand the backing being bonded together by bond comprising Turkey red oil.

5. A copy pad having a backing and a gelatinous copy, the copy mass andthe backing being bonded together by a bond comprising sulphonatedcastor oil.

6. A copy pad comprising a backing, a gelatinous copy mass and anintermediate bond of Turkey red oil.

7. The method of preparing a copy pad which comprises applying to abacking a solution of a sulphonated oil to forms. flexible bonding fllm,drying the fllm and applying a layer of a gelatinous copy mass to thetreated backing.

8. The method of preparing a copy pad which comprises coating asized-backing with a solu tion of a sulphonated oil to form a flexiblebond ing layer, drying said layer and applying a laye of a copy mass tosaid bonding layer.

9. The method or preparing a copy pad which comprises coating a backingwith a solution of Turkey red oil to form a flexible bonding layer andapplying a layer of a gelatinous copy mass to said bonding layer.

10. The method of preparing a copy pad which comprises coating a sizedbacking with a solution or sulphonated castor oil to form a flexiblebonding layer, drying said layer and applying a layer of a copy mass tosaid bonding layer.

11. The method of preparing a copy pad which comprises applying to abacking a size solution containing Turkey red oil to form a flexiblebonding layer, drying said layer and applying a layer of a gelatinouscopy mass to said bonding layer.

12. The method of preparing a copy pad which comprises applying to abacking a size solution containing Turkey red oil, a gelatinous sizingagent and a tanning agent to form a flexible bonding layer, drying saidlayer and applying a layer of a gelatinous copy mass to said bondinglayer.

13. The method of preparing a copy pad which comprises coating a backingwith a size solution containing at least 3% of Turkey red oil to form aflexible bonding layer, drying said layer and applying a layer of agelatinous copy mass to said bonding layer.

14. The method of preparing a copy pad which comprises coating a backingwith a solution con- 7 taining about 5% of a sulphonated oil to form aflexible bonding layer, drying said layer and applying a layer of agelatinous copy mass to said bonding layer.

15. The method of preparing a copy pad which comprises coating a backingwith solution containing at least 3% of sulphonated oil to form aflexible bonding layer, drying said layer and applying a layer of agelatinous copy mass to sai bonding layer.

WILLIAM HOSKINS, JR.

